The present invention relates to building construction, and more particularly to a device that aids a worker in erecting roof trusses atop a building being framed.
The construction of the frame of a conventional building such as a wood-frame house or the like generally starts with the construction of the wall sections. Once the wall sections have been built and attached to the foundation and to one another, the roof frame is then erected atop the walls. A roof frame conventionally is formed of a series of spaced-apart trusses, typically of generally triangular shape, that are attached atop the walls. The trusses define the overall shape of the roof, in terms of its pitch and so forth, and form the structural supports for other frame members that are attached to the trusses, such as a ridge beam that extends along the ridge of the roof.
The conventional process for erecting trusses is awkward at the least, and can be hazardous for the workers who must clamber atop the roof and receive a truss from an overhead crane. The workers must guide the truss into proper position and then must secure the truss in position by nailing wood supports between the newly erected truss and a previously secured one.
The present invention was developed to facilitate the process of erecting roof trusses. A device in accordance with the invention comprises a portable platform of a size and weight easily lifted and manipulated by a single worker. The platform is configured to fit over the upper ends of the chords of a truss that has already been secured in place so that it can support a worker. A worker can stand on the platform, which positions the worker in a suitable position to be able to work on an adjacent truss that is not yet secured. By using a pair of the devices, the worker can move from truss to truss, from one end of the roof to the other. When the worker is finished securing a truss, he moves the device that is not currently in use from one truss to the truss that he has just finished securing in place, and then steps from the device currently in use onto the other device so that the worker is then supported on the newly secured truss and in position to guide a new truss into position so that it can be secured. This process is repeated until all trusses have been secured.
In accordance with a preferred embodiment of the invention, the device comprises a base for the worker to stand on, and a pair of support arms attached to the platform adjacent one end thereof. The support arms extend upward from the platform. The upper ends of the support arms are attached to or define truss grips configured to fit over the tops of the truss chords on opposite sides of the peak so as to suspend the platform from the truss. The support arms and truss grips are sufficiently rigid and fit closely over the chords such that the support arms remain substantially vertical and the platform remains substantially horizontal when a worker is supported on the platform, using only the support provided by the chords. This is important because trusses in some cases do not have any vertical members against which the lower portion of the device can abut to resist rotation of the device as a result of the worker""s weight on the platform. Because the platform is located to one side of the truss, the worker""s weight exerts a moment on the device tending to rotate the device about the chords of the truss. This moment is resisted entirely by the engagement between the support arms and truss grips and the chords of the truss.
The invention also encompasses a method of erecting trusses, in which a first platform is suspended from a first truss that has been secured in place, a worker stands on the platform and secures a second truss in place adjacent the first truss, the worker suspends a second platform from the second truss and steps onto the second platform, the worker secures a third truss in place adjacent to the second truss, and the worker then moves the first platform from the first truss onto the third truss.